► As a crucial step in nuclear-based hydrogen production based on Cu-Cl cycle, the performance analysis of heat transfer process is of paramount importance. However, as…
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▼ As a crucial step in nuclear-based hydrogen production based on Cu-Cl cycle, the performance analysis of heat transfer process is of paramount importance. However, as a newly built system, the major obstacle of applying standard performance analysis to the heat transfer process is the sparse data. In this thesis, the methodology of Monte-Carlo Simulation-based (MCS-based) performance analysis is developed, and it is shown that this method can be used to deal effectively with the problems caused by sparse data in the heat transfer process. This method expanded the database successfully and carried out the Monte-Carlo simulation through expanded database. The details of the heat transfer process in a nuclear-based hydrogen production based on a four-step Cu-Cl cycle is firstly listed and discussed. Afterwards, the modelling of the MCS-based performance analysis of heat transfer process is proposed and explained step by step. The confidence interval of the simulation results is demonstrated since the variations in results is a major issue for any performance analysis based on simulations. The final result indicated that the MCS-based performance analysis is a reasonable performance analysis method that can be used to evaluate the performance of the heat transfer process in the nuclear-based hydrogen production based on Cu-Cl cycle through sparse data.
Advisors/Committee Members: Lu, Lixuan.

Lu, Y. (2014). Monte-Carlo-simulation-based performance analysis of the heat transfer process in nuclear-based hydrogen production based on Cu-Cl Cycle. (Thesis). University of Ontario Institute of Technology. Retrieved from http://hdl.handle.net/10155/454

Note: this citation may be lacking information needed for this citation format:Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Lu, Yi. “Monte-Carlo-simulation-based performance analysis of the heat transfer process in nuclear-based hydrogen production based on Cu-Cl Cycle.” 2014. Thesis, University of Ontario Institute of Technology. Accessed March 21, 2019.
http://hdl.handle.net/10155/454.

Note: this citation may be lacking information needed for this citation format:Not specified: Masters Thesis or Doctoral Dissertation

Note: this citation may be lacking information needed for this citation format:Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Lu Y. Monte-Carlo-simulation-based performance analysis of the heat transfer process in nuclear-based hydrogen production based on Cu-Cl Cycle. [Thesis]. University of Ontario Institute of Technology; 2014. Available from: http://hdl.handle.net/10155/454

Note: this citation may be lacking information needed for this citation format:Not specified: Masters Thesis or Doctoral Dissertation

► The goal of this thesis was to explore the effects of dose resolution, respiratory variation and dose calculation method on dose accuracy. To achieve this,…
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▼ The goal of this thesis was to explore the effects of dose resolution, respiratory variation and dose calculation method on dose accuracy. To achieve this, two models of lung were created. The first model, called TISSUE, approximated the connective alveolar tissues of the lung. The second model, called BRANCH, approximated the lungs bronchial, arterial and venous branching networks. Both models were varied to represent the full inhalation, full exhalation and midbreath phases of the respiration cycle.
To explore the effects of dose resolution and respiratory variation on dose accuracy, each model was converted into a CT dataset and imported into a MonteCarlo simulation. The resulting dose distributions were compared and contrasted against dose distributions from MonteCarlo simulations which included the explicit model geometries. It was concluded that, regardless of respiratory phase, the exclusion of the connective tissue structures in the CT representation did not significantly effect the accuracy of dose calculations. However, the exclusion of the BRANCH structures resulted in dose underestimations as high as 14% local to the branching structures. As lung density decreased, the overall dose accuracy marginally decreased.
To explore the effects of dose calculation method on dose accuracy, CT representations of the lung models were imported into the Pinnacle3 treatment planning system. Dose distributions were calculated using the collapsed cone convolution method and compared to those derived using the MonteCarlo method. For both lung models, it was concluded that the accuracy of the collapsed cone algorithm decreased with decreasing density. At full inhalation lung density, the collapsed cone algorithm underestimated dose by as much as 15%. Also, the accuracy of the CCC method decreased with decreasing field size.
Further work is needed to determine the source of the discrepancy.
Advisors/Committee Members: Sidhu, Narinder, Pywell, Rob, Mayer, Monique, Xiao, Chijin, Kendall, Edward, Igarashi, Ru, Rogers, Dave.

►MonteCarlo (MC) methods for radiotherapy dose calculation are widely accepted as capable of achieving high accuracy. In particular, MC calculations have been demonstrated to…
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▼MonteCarlo (MC) methods for radiotherapy dose calculation are widely accepted
as capable of achieving high accuracy. In particular, MC calculations have been
demonstrated to successfully reproduce measured dose distributions in complex situations where alternative dose calculation algorithms failed (for example, regions of
charged particle disequilibrium). For this reason, MC methods are likely to play
a central role in radiotherapy dose calculations and dose verification in the future.
However, clinical implementations of MC calculations have typically been limited due
to the high computational demands. In order to improve the feasibility of using MC
simulations clinically, the simulation techniques must be made more efficient.
This dissertation presents a number of approaches to improve the efficiency of
MC dose calculations. One of the most time consuming parts of source modeling
is the simulation of the secondary collimators, which absorb particles to define the
rectangular boundaries of radiation fields. The approximation of assuming negligible
transmission through and scatter from the secondary collimators was evaluated for
accuracy and efficiency using both graphics processing unit (GPU)-based and central processing unit (CPU)-based MC approaches. The new dose calculation engine,
gDPM, that utilizes GPUs to perform MC simulations was developed to a state where
accuracy comparable to conventional MC algorithms was attained. However, in GPU-
based dose calculation, source modeling was found to be an efficiency bottleneck. To
address this, a sorted phase-space source model was implemented (the phase-space-
let, or PSL model), as well as a hybrid source model where a phase-space source was
used only for extra-focal radiation and a point source modeled focal source photons.
All of these methods produced results comparable with standard CPU-based MC
simulations in minutes, rather than hours, of calculation time. While maintaining
reasonable accuracy, the hybrid source model increased source generation time by a
factor of ~2-5 when compared with the PSL source model. A variance reduction
technique known as photon splitting was also implemented into gDPM, to evaluate
its effectiveness at reducing simulation times in GPU calculations.
Finally, an alternative CPU-based MC dose calculation technique was presented
for specific applications in pre-treatment dose verification. The method avoids the
requirement of plan-specific MC simulations. Using measurements from an electronic
portal imaging device (EPID), pre-calculated MC beamlets in a spherical water phantom were modulated to obtain a dose reconstruction.
Advisors/Committee Members: Zavgorodni, Sergei (supervisor), Jirasek, Andrew (supervisor).

► In this thesis we examine methods for measuring entanglement entropy in spin-1/2 Heisenberg systems using quantum MonteCarlo in the valence bond basis. We begin…
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▼ In this thesis we examine methods for measuring entanglement entropy in spin-1/2 Heisenberg systems using quantum MonteCarlo in the valence bond basis. We begin by presenting the quantum MonteCarlo techniques used in this research. We then use these techniques to directly compare the recently proposed valence bond entanglement entropy to the standard definition of entanglement entropy: the von Neumann entanglement entropy. We find that the valence bond entanglement entropy does not give a bound on the von Neumann entanglement entropy, and that it exhibits a multiplicative logarithmic correction to the area law that is not present in the scaling of the von Neumann entanglement entropy. We then present a method to measure higher orders of the generalized Renyi entanglement entropies using valence bond quantum MonteCarlo, and show results for the second Renyi entropy. We find the results converge to the exact results for one dimensional Heisenberg spin-1/2 chains, and see that the scaling of the second Renyi entropy follows an area law in the two dimensional Heisenberg ground state.

► This thesis describes the development of a novel comprehensive MonteCarlo simulation code, ARTEMIS, for the investigation of electron-hole pair transport mechanisms in a-Se x-ray…
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▼ This thesis describes the development of a novel comprehensive MonteCarlo simulation code, ARTEMIS, for the investigation of electron-hole pair transport mechanisms in a-Se x-ray imaging detectors. ARTEMIS allows for modeling of spatiotemporal carrier transport in a-Se, combining an existing MonteCarlo simulation package, PENELOPE, for simulation of x-ray and secondary electron interactions and new routines for electron-hole pair transport with three-dimensional spatiotemporal signal output considering the effects of applied electric field. The detector Swank factor, an important imaging performance metric is calculated from simulated pulse-height spectra and shown to depend on incident x-ray energy and applied electric field. Simulation results are compared to experimental measurements and are found to agree within 2%. Clinical x-ray spectra are also used to study detector performance in terms of energy weighting and electronic noise. Simulation results show energy-weighting effects are taken into account in the ARTEMIS model, where the Swank factor and DQE have a higher dependence on the high-energy incident x rays due to increased carrier yield. Electronic noise is found to widen the pulse-height spectra and degrade the Swank factor. The effect of recombination algorithms and burst models are studied. A comparison of a first-hit algorithm and a nearest-neighbor approach shows no significant difference in the simulation output while achieving reduced simulation time. The examination of the initial generation of carriers in the burst shows that the recombination efficiency of carriers is dependent on the carrier density and electric field. Finally, the spatial resolution characteristics of a flat-panel a-Se detector are studied by using the ARTEMIS model for spatial output and image generation. The modulation transfer functions are calculated from simulated detector point response functions for monoenergetic and clinical radiation qualities.

In this study, a probabilistic design method for
the design of wastewater treatment plants (WWTP) that enables the
quantification of the degree of compliance to the effluent
standards in terms of probability has been proposed. The developed
design method is a model-based approach in which relevant sources
of uncertainty are expressed in terms of probability distribution
functions and their combined effect on the distribution of the
effluent quality is quantified by MonteCarlo…

The goal of this project is to develop an
application to correct the scattered radiation in a cone beam
computed tomography scan (CBCT). A MonteCarlo simulation is used
to estimate the scattered radiation which is a numerical
replication of a CBCT acquisition. This project has been divided
into two sections : the validation of the physics for this specific
application and the development of the application. The validation
consisted in reproducing the results obtained with Geant4 in
GPUMCD. Geant4 is the reference platform and GPUMCD is the platform
studied. Both are MonteCarlo…

► This thesis contains the author’s work in and contributions to the field of MonteCarlo sampling for undirected graphical models, a class of statistical model…
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▼ This thesis contains the author’s work in and contributions to the field of MonteCarlo sampling for undirected graphical models, a class of statistical model commonly used in machine learning, computer vision, and spatial statistics; the aim is to be able to use the methodology and resultant samples to estimate integrals of functions of the variables in the model. Over the course of the study, three different but related methods were proposed and have appeared as research papers. The thesis consists of an introductory chapter discussing the models considered, the problems involved, and a general outline of MonteCarlo methods. The three subsequent chapters contain versions of the published work. The second chapter, which has appeared in (Hamze and de Freitas 2004), is a presentation of new MCMC algorithms for computing the posterior distributions and expectations of the unknown variables in undirected graphical models with regular structure. For demonstration purposes, we focus on Markov Random Fields (MRFs). By partitioning the MRFs into non-overlapping trees, it is possible to compute the posterior distribution of a particular tree exactly by conditioning on the remaining tree. These exact solutions allow us to construct efficient blocked and Rao-Blackwellised MCMC algorithms. We show empirically that tree sampling is considerably more efficient than other partitioned sampling schemes and the naive Gibbs sampler, even in cases where loopy belief propagation fails to converge. We prove that tree sampling exhibits lower variance than the naive Gibbs sampler and other naive partitioning schemes using the theoretical measure of maximal correlation. We also construct new information theory tools for comparing different MCMC schemes and show that, under these, tree sampling is more efficient. Although the work discussed in Chapter 2 exhibited promise on the class of graphs to which it was suited, there are many cases where limiting the topology is quite a handicap. The work in Chapter 3 was an exploration in an alternative methodology for approximating functions of variables representable as undirected graphical models of arbitrary connectivity with pairwise potentials, as well as for estimating the notoriously difficult partition function of the graph. The algorithm, published in (Hamze and de Freitas 2005), fits into the framework of sequential MonteCarlo methods rather than the more widely used MCMC, and relies on constructing a sequence of intermediate distributions which get closer to the desired one. While the idea of using “tempered” proposals is known, we construct a novel sequence of target distributions where, rather than dropping a global temperature parameter, we sequentially couple individual pairs of variables that are, initially, sampled exactly from a spanning treeof the variables. We present experimental results on inference and estimation of the partition function for sparse and densely-connected graphs. The final contribution of this thesis, presented in Chapter 4 and also in (Hamze and de Freitas…

► An approach for generating radiation intensity maps, comprised of a mobile robotic platform and an integrated radiation model, is presented, and its ability to generate…
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▼ An approach for generating radiation intensity maps, comprised of a mobile robotic platform and an integrated radiation model, is presented, and its ability to generate accurate radiation maps in simulation studies as well as real-life exposure scenarios are investigated.
The radiation intensity mapping approach described here consists of two stages. First, radiation intensity samples are collected using a radiation sensor mounted on a mobile robotic platform, reducing the risk of exposure to humans from an unknown radiation field. Next, these samples, which need only to be taken from a subsection of the entire area being mapped, are then used to calibrate a radiation model. This model is then used to predict the radiation intensity field throughout the rest of the area.
In this thesis, the technical details of both the prototype mobile robotic platform and the mathematical models for the radiation and map generation algorithms are presented in depth. The performance of the approach is evaluated in simulation studies and experiments in the lab. The sensitivity of the performance of the platform to changes in the number and orientation of the locations where the robot gathers samples from to calibrate the model for the given exposure scenario is analyzed quantitatively.
The results show that the developed system is effective at achieving the goal of generating radiation maps using sparse data.
Advisors/Committee Members: Nokleby, Scott, Waller, Ed.

► In order to be able to qualify and quantify radiation exposure in terms of dose, a Fastscan whole body counter must be calibrated correctly. Current…
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▼ In order to be able to qualify and quantify radiation exposure in terms of dose, a Fastscan whole body counter must be calibrated correctly. Current calibration methods do not take the full range of body types into consideration when creating efficiency curve calibrations. The goal of this work is the creation of a MonteCarlo (MCNP) model, that allows the simulation of efficiency curves for a diverse population of subjects. Models were created for both the Darlington and the Pickering Fastscan WBCs, and the simulations were benchmarked against experimental results with good agreement. The Pickering Fastscan was found to have agreement to within ??9%, and the Darlington Fastscan had agreement to within ??11%. Further simulations were conducted to investigate the effects of increased body fat on the detected activity, as well as locating the position of external contamination using front/back ratios of activity. Simulations were also conducted to create efficiency calibrations that had good agreement with the manufacturer's efficiency curves. The work completed in this thesis can be used to create efficiency calibration curves for unique body compositions in the future.
Advisors/Committee Members: Waller, Ed.

► There is a growing concern from both national regulators and the International Atomic Energy Agency (IAEA) about the threat posed by attacks against iconic targets…
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▼ There is a growing concern from both national regulators and the International
Atomic Energy Agency (IAEA) about the threat posed by attacks against iconic targets such as nuclear power plants. This has led to an increased desire to be able to objectively measure the effectiveness of the physical security of these sites to prevent theft or sabotage of the nuclear and radiological material. Currently verification of physical protection systems is done using subjective expert opinion as well as time consuming and expensive live exercises. A method that allows experts to design and test a facility in the absence of live action exercises using larger sample sizes would be highly desirable. To _ll the niche a synthetic environment model was designed around the force on force simulation program STAGE to allow the full 3-D simulation of a nuclear facility. This allows for simple user modifications to the model, allowing many scenarios to be tested. Many detectors were added to more accurately reflect the types of sensors present at a nuclear facility. Having modeled the facility and the probabilities associated with various events, Monte-Carlo methods were applied to obtain statistics on how effective the guard force was at stopping the adversarial force. This technique can be used to give experts more robust, simple to use tools for the design and verification of physical protection systems.
Advisors/Committee Members: Waller, Edward.